Extended Data Fig. 3: Stochastic model predictions on actin network architecture.
From: Extracellular fluid viscosity enhances cell migration and cancer dissemination
a, Representative visualization of stochastic model results with actin filaments shown in green, barbed ends as red dots, and pointed ends as blue dots. To reach steady state, the simulation was allowed to run for 6 s during which the network grew only against membrane tension from 0 to ~1250 nm as indicated by the red arrowheads. Subsequently, the network grew against the membrane tension plus the indicated viscous forces (0.8 or 8 cP). b, Actin network density over time of individual simulation runs. c, Growth velocity of the actin network front over time. Each line (b,c) represents individual simulation runs. d, Growth velocity of the actin network front over time, averaged from 20 individual simulation runs per condition in (c). e, Time-averaged actin network front growth velocity over 4 s following the application of viscous forces. f, Temporal variation in density of filaments in three different angle bins. Zero degrees represent filaments perpendicular to network edge while 90 degrees are parallel to the edge. Red arrowhead indicates time instant of viscous force application. The filament density at each angle bins is flat at 0.8 cP after turning on the viscous forces. At 8 cP, there is an increase in filament density across all the bins indicating a denser actin network at the cell edge facing the viscous resistance. g, Actin filament, capped barbed end, and pointed end density quantified at two different viscous forces. After application of the 8 cP viscous force, there is a sharp rise of pointed ends and increase in filament density, presumably resulting from increased ARP2/3-mediated nucleation. In e, f and g, data are mean ± s.d. from 20 runs per condition. Unpaired t-test was used in e.
